html, body, .page {
    height: 100%;
}
body {
    background-color: #5acdfc;
    color: #333;
    margin: 0;
    padding: 0;
}
img {
    border: 0;
    display: block;
    height: auto;
    width: 100%;
}
.page {
    display: none;
}
.mask {
    background-color: #000;
    opacity: 0.75;
    display: none;
    position: fixed;
    left: 0;
    top: 0;
    width: 100%;
    height: 100%;
    z-index: 2;
}